title: The non-invasive tear film break-up time in normal children.
abstract: OBJECTIVE
  To perform an objective evaluation of the non-invasive tear break-up time (NITBUT) and lipid layer interferometry in normal children.
  
  
  METHODS
  Children with no known ocular surface disease or anterior segment abnormality were evaluated. We excluded patients with disorders affecting lid margins or tear film composition. NITBUT and lipid layer interferometry were performed using a Keeler tearscope mounted on a slit lamp. The time from eye opening to the first distortion of the grid was noted. The average of three readings was taken as the NITBUT.
  
  
  RESULTS
  Thirty-six children (71 eyes) were included (mean age 7.64 years, range 2.16-15.83 years). Mean NITBUT was 21.76 ± 4.06 s (range 14.9-30.95). This is significantly higher in comparison to recent adult studies utilising the tearscope. Twenty-four children allowed tearscope lipid layer interferometry. Eighteen demonstrated grade 1 and six demonstrated grade 2. These grades are within the normal tear film range.
  
  
  CONCLUSIONS
  To our knowledge, this prospective study is the first to evaluate NITBUT in normal children. The results demonstrate that NITBUT is greater in children in comparison to adults. These normative data are a useful benchmark for further research into tear film instability in children.
authors.affiliation: The Clinical and Academic Department of Ophthalmology, Great Ormond Street Hospital for Children, London, UK.
authors.forename: Sophie M
authors.initials: SM
authors.lastname: Jones
authors.forename: Ken K
authors.initials: KK
authors.lastname: Nischal
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007368:Interferometry; D008055:Lipids; D008297:Male; D011446:Prospective Studies; D013666:Tears / Q000378:metabolism*
chemical_list: D008055:Lipids
keywords: Child health (paediatrics); Diagnostic tests/Investigation; Ocular surface; Physiology; Tears